PROJECT SUMMARY?Hydrostasis, Inc. has developed a wearable hydration monitoring system that provides real-time tracking of total body water (TBW) status and provides alerts to users and remote monitors to ensure timely intervention when hydration deviates from an optimal range. This technology developed for healthy athletes has the potential to transform how millions of older adults with heart failure (HF) and their physicians monitor and respond to fluctuations in TBW. However, adapting the technology for use in this population may require a) tailoring the hydration detection algorithm to accommodate differences related to patient age and disease status and b) tailoring the alert system to meet the needs of older adults and their healthcare providers. If successfully adapted, this technology could 1) improve patient-centered control of hydration status, 2) reduce physician burden for disease management, 3) reduce cost / burden of inadequate medication management and hospitalization rates associated with weight-based hydration monitoring, and 4) improve patient outcomes and quality of life. For many patients, fluid retention (congestion) is a pronounced symptom of the underlying cardiac insufficiency, and the presence of excess fluid uniformly signals a problem that must be addressed to avoid costly hospitalizations and increased risk of near-term mortality associated with decompensation. Proper management requires frequent monitoring of TBW status and intervention in response to fluid accumulation, but the current standard is daily weight monitoring, which has only 9% sensitivity to detect clinically relevant changes. The wearable Hydrostasis sensor uses diffuse near-infrared spectroscopy to assess hydration in tissue up to 2 cm below the skin. The proposed SBIR Phase I project is a step toward adapting this technology to provide continuous at-home monitoring plus threshold-based alerts for patients and physicians. Aim 1. Adapt the Hydrostasis monitoring system for use in older adults. Tasks: 1) Assess performance of the current algorithm over one week in 30 older adults. 2) Refine the algorithm. 2) Assess how the refined algorithm?s personalized hydration index (PHI) compares to urine specific gravity in older adults. Milestones: 1) Enroll 15 males, 15 females age 65 +; 2) obtain ? 4 hours of data per day for 7 days on ? 80% of participants; 3) obtain 3-day use test data on ? 80% of participants; 4) PHI sensitive to ? 2% change in TBW. Aim 2. Adapt the Hydrostasis alert system to provide alerts tailored for older adult users and physicians. Tasks: 1) Convene patient & physician focus groups to identify user preferences for monitoring platforms/alerts, 2) Adapt platforms to accommodate preferences and deliver alerts when hydration status reaches clinically actionable thresholds. Milestones: 1) Enroll 10 males, 10 females age 65+ with HF; 2) Enroll 6 male, 6 female cardiologists; 3) Develop spec lists of prioritized user preferences for app and platform elements; 4) Integrate ? 90% of high- priority and ? 70% of medium-priority preferences; 5) Refined software has SUS ? 73 for patients and ? 65 for physicians. Future work will further refine the algorithm and threshold-based alerts for use in each stage of HF.